Stereo disparity facilitates view generalization during shape recognition for solid multipart objects

Abstract

Current theories of object recognition in human vision make different predictions about whether the recognition of complex, multipart objects should be influenced by shape information about surface depth orientation and curvature derived from stereo disparity. We examined this issue in five experiments using a recognition memory paradigm in which observers (N = 134) memorized and then discriminated sets of 3D novel objects at trained and untrained viewpoints under either mono or stereo viewing conditions. In order to explore the conditions under which stereo-defined shape information contributes to object recognition we systematically varied the difficulty of view generalization by increasing the angular disparity between trained and untrained views. In one series of experiments, objects were presented from either previously trained views or untrained views rotated (15°, 30°, or 60°) along the same plane. In separate experiments we examined whether view generalization effects interacted with the vertical or horizontal plane of object rotation across 40° viewpoint changes. The results showed robust viewpoint-dependent performance costs: Observers were more efficient in recognizing learned objects from trained than from untrained views, and recognition was worse for extrapolated than for interpolated untrained views. We also found that performance was enhanced by stereo viewing but only at larger angular disparities between trained and untrained views. These findings show that object recognition is not based solely on 2D image information but that it can be facilitated by shape information derived from stereo disparity.

Keywords:

• Object recognition
• View generalization
• Stereo disparity

The authors wish to thank Candy Patterson and Pamela Arnold for their contribution to the study.

This work was supported by an ESRC/EPSRC (Economic and Social Research Council/Engineering and Physical Sciences Research Council) grant [grant number RES-062-23-2075] awarded to E.C.L.

Notes

1 We do not claim that stereo disparity provides the only source of shape information about local surface orientation and curvature. Indeed, cues such as shadow and shading gradients, texture, and nonaccidental properties of edge features that are computable from mono input could also be used to infer surface properties. However, surface depth orientation and part boundaries at surface intersections are enhanced under conditions of stereo viewing due to binocular disparity.